This disclosure relates to a gas turbine engine component, such a low-leakage air seal.
Gas turbine engines typically include a fan section, a compressor section, a combustor section and a turbine section. The fan section may be housed in a fan case. During operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases are communicated through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.
Gas turbine engines use various types of sealing concepts to control or prevent leakage of air from higher pressure areas to lower pressure areas. Locations can include secondary (internal) flow seals intended to isolate cooler, lower pressure air for thermal conditioning of components (disks, shafts, etc.) and for establishing appropriate thermal environments for oil filled bearing compartments and other thermally sensitive components. For example, the source of secondary/ internal air comes from the engine flow path. Removal of this air—often already partially compressed via the engine's compression system—represents a loss to engine efficiency.
In another example, seals where radial clearances between rotating knife edges and static cases form gaps through which higher pressure flow can circulate to lower pressure regions. In this example, the undesired circulation of flow detracts from either compressor (where work is added to the fluid to increase pressure) or turbine (where work is removed from the fluid thereby reducing pressure) efficiency. This leakage also has an adverse and more pronounced impact on component and overall cycle efficiency. Current sealing concepts between rapidly rotating components and static structures often use a knife-edge rotating against an abradable surface (for example, honeycomb, porous metal, aluminum polyester or another material). During engine operation, a combination of axial and radial displacements create wear, which can degrade the effectiveness of the seal during subsequent operation.